Process for the preparation of halogenated 2,2-bis(trifluoromethyl)-1,3-dioxolanes

ABSTRACT

A process for the production of a halogenated 2,2-bis(trihaloalkyl)-1, 3-dioxolane of the formula ##STR1## wherein R f  is perhaloalkyl comprising a 2,2-bis(trihaloalkyl)-1,3-dioxolane in the presence of at least one of La, Ni, Sn, Zn Fe, Co or Cu is disclosed. 
     A process for the production of a halogenated 2,2-bis(trihaloalkyl)-1,3-dioxolane of the formula ##STR2## wherein X is Cl and each Y is independently Cl or F and wherein at least one Y is F, comprising fluorinating a halogenated 2,2-bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-dioxolane in the presence of a catalyst which is preferably Cr 2  O 3  is disclosed. 
     A process for the production of a 2,2-bis(trihaloalkyl)-1,3-dioxole of the formula ##STR3## comprising dehalogenating substantially only a corresponding trans-2,2-bis(perhaloalkyl)-4,5-difluoro-4, 5-dichloro-1,3-dioxolane is disclosed.

This is a division of application Ser. No. 07/759,095, filed Sep. 6,1991 now U.S. Pat. No. 5,177,224, which is a continuation of applicationSer. No. 07/399,100, filed Aug. 28, 1989 abandoned.

BACKGROUND OF THE INVENTION

The invention concerns a catalytic process for the preparation ofhalogenated 2,2-bis(trifluoromethyl)-1,3-dioxolanes.

2,2-Bis(trifluoromethyl)-1,3-dioxolane is a known compound which may behalogenated according to a number of known methods to produce varioushalo-isomers at the 4,5 or 4 and 5 positions. For example, U.S. Pat. No.2,925,424 describes a batch photochemical chlorination of2,2-bis(trifluoromethyl)-1,3-dioxolane. The reaction was conducted at50° C. for 2.5 hours. A 68% yield of2,2-bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-dioxolane was obtainedupon fractionation of crude product. See Example 9.

U.S. Pat. No. 4,535,175 discloses a batch photochemical chlorination of2,2-bis(trifluoromethyl)-1,3-dioxolane to yield a mixture of di-, tri-and tetra-chloro derivatives. The reaction proceeds rather slowly.Example 1 of the patent details the production of2,2-bis(trifluoromethyl)-4,4,5-trichloro-5-fluoro-1,3-dioxolane byreacting 2,2-bis(trifluoromethyl)-4,4,5,5,-tetrachloro-1,3-dioxolane, HFand antimony chloride at 70° C. for 5 hours.

U.S. Pat. No. 3,794,791 discloses a batch photochlorination of2,2-bis(trifluoromethyl)-1,3-dioxolane at -15° C. Example 1 describesthe synthesis of 2,2-bis(trifluoromethyl)-4-chloro-1,3-dioxolane.Example 2 of the patent describes the synthesis of2,2-bis(trifluoromethyl)-4,5-dichloro-1,3-dioxolane.

G.B. 1,361,346 discloses the preparation of2,2-bis(trifluoromethyl)-4,5-dichloro-4,5-difluoro-1,3-dioxolane byfluorinating 2,2-bis(trifluoromethyl)-4,4,5,5,-tetrachloro-1,3-dioxolane with SbF₃ /SbCl₅ at 120° C.

SUMMARY OF THE INVENTION

The invention provides a process for the preparation of2,2-bis(perhaloalkyl)-4,4,5,5-tetrachloro-1,3-dioxolane by chlorinating2,2-bis(perhaloalkyl)-1,3-dioxolane with a source of chlorine in thepresence of a catalyst which contains at least one of La, Ni, Sn, Zn Co,Fe, or Cu.

The invention also provides a process for the preparation of fluorinated2,2-bis(perhaloalkyl)-1,3-dioxolanes of the formula ##STR4## wherein Xis Cl, each Y is independently Cl or F and at least one Y is F, and eachR_(f) is independently perhaloalkyl in which the alpha carbon issubstituted by at least one fluorine atom.

The process comprises fluorinating2,2-bis(perhaloalkyl)-4,4,5,5-tetrachloro-1,3-dioxolane with a source offluorine under fluorination conditions, so as to effectfluorine-chlorine exchange, in the presence of a catalyst which is acatalyst as noted above in the chlorination reaction or is chromium(III) oxide, i.e., Cr₂ O₃ or one or more of a metal supported on carbonwherein the metals are chosen from Cr, Co, La, Fe, Ni, Cu, Sn, or Zn.

DETAILED DESCRIPTION

Preferably, R_(f) is trifluoromethyl. The2,2-bis(perhaloalkyl)-1,3-dioxolane starting material for thechlorination is a known compound which may be readily prepared byreacting perfluoroacetone and ethylene chlorohydrin under basicconditions as described in U.S. Pat. No. 2,925,424.

The chlorination is preferably conducted in the vapor phase, and ispreferably conducted continuously. However, the reaction may beconducted in the liquid phase using the reactants as solvents, at thesame temperatures noted for the vapor phase, under autogenous pressure.Preferred temperatures for the reaction are 250°-300° C. The molar ratioof chlorine to 2,2-bis(perhaloalkyl)-1,3-dioxolane is preferably about4:1 to 10:1, more preferably about 4:1 to 5:1. The reaction time isgenerally about 1 to 120 seconds, and is preferably about 30 to 60seconds. The reaction pressure is preferably about 1 to 20 atmospheres,more preferably about 10 to 20 atmospheres. The preferred source ofchlorine is chlorine gas. The catalyst metal may be in the form of anysoluble compound of the metal such as the oxide, oxyhalide, halide,pseudohalide, nitrate, sulfate, or organic salt such as acetate andpropionate. The halides include chlorides, fluorides and bromides. Thepseudohalides include cyanides, cyanates and thiocyanates. The form ofthe catalyst is not critical and may be pellets, powders or granules.Preferably, the catalysts are used in a fixed bed; however, fluidizedbed reactors may also be used. Preferably, the catalysts are in the formof their chlorides, and preferably are supported on carbon. Thepreferred catalyst for the chlorination is CuCl₂ /C.

General Procedure for Preparing Catalysts MCl_(x) /C

The desired amount of metal chloride was dissolved in water (35 to 75mL) and the entire solution poured over 40 g of commercial carbongranules (Girdler 411, 0.32 cm pellets). The resulting mixture wasallowed to stand at room temperature for one hour and was then placed ina vacuum oven at 110° C. for 16 to 24 hours to remove the water. Thecatalyst was then pretreated by heating in an atmosphere of nitrogen gasat 400° C. followed by heating in HF at 400° C. prior to its use as afluorination catalyst. For chlorination reactions, the catalyst washeated in an atmosphere of nitrogen gas at 400° C. followed by adjustingthe temperature to the desired value and treatment with chlorine gas.Preferably, 0.1-30% b.w. based on the support of active metal isincorporated in the catalyst.

Catalyst Preparation

The following catalysts were prepared by the general procedure forMCl_(x) /C:

    ______________________________________                                        CoCl.sub.2 /C 35 g CoCl.sub.2.6H.sub.2 O/35 mL H.sub.2 O                      FeCl.sub.3 /C 39.7 g FeCl.sub.3.6H.sub.2 O/35 mL H.sub.2 O                    ZnCl.sub.2 /C 20.44 g ZnCl.sub.2 /75 mL H.sub.2 O                             NiCl.sub.2 /C 34.94 g NiCl.sub.2 2.6H.sub.2 O/35 mL H.sub.2 O                 LaCl.sub.3 /C 62.43 g LaCl3.7H.sub.2 I/75 mL H.sub.2 O                        CrCl.sub.3 /C 39.17 g CrCl.sub.3.6H.sub.2 O/60 mL H.sub.2 O                   SnCl.sub.2 /C 38.36 g SnCl.sub.2.2H.sub.2 O/70 mL H.sub.2 O                   CuCl.sub.2 /C 25.06 g CuCl.sub.2.2H.sub.2 O/70 mL H.sub.2 O                   ______________________________________                                    

Cr₂ O₃ is commercially available and was treated with HF as describedabove prior to its use as a fluorination catalyst.

The catalysts having differing anions are prepared analogously.

The fluorination is preferably conducted in the vapor phase, and ispreferably conducted continuously. The reaction may be conducted in theliquid phase as indicated for the chlorination. The reaction temperatureis preferably 150° to 350° C., more preferably 150° to 200° C. Thepreferred source of fluorine is HF. The molar ratio of HF to2,2-bis(perhaloalkyl)-4,4,5, 5-tetrachloro-1,3-dioxolane is preferablyabout 2:1 to 10:1, more preferably about 2:1 to 5:1. Preferred reactiontime is about 1 to 120 seconds, more preferably about 30 to 60 seconds.The preferred catalyst for the fluorination is Cr, more preferablyunsupported Cr₂ O₃.

The production of the fluoro-compounds may be conducted in two steps,with, e.g., isolation of a2,2-bis(perhaloalkyl)-4,4,5,5-tetrachloro-1,3-dioxolane intermediate, ormay be conducted in one enclosure with the addition of the fluorinesource preferably after substantial completion of the first reaction.

The catalysts of the invention are extremely active and selective. Inthe fluorination, where Cr₂ O₃ is the catalyst, the ratio of trans tocis isomers is desirably high.

The products of the process of the invention are useful as intermediatesin the production of perhalodioxoles of the formula ##STR5## bydehalogenation of the appropriate precursor according to conventionalprocesses, for example, as disclosed in U.S. Pat. Nos. 4,535,175,3,865,845, and 3,978,030.

Preferably,trans-2,2-bis(perhaloalkyl)-4,5-difluoro-4,5-dichloro-1,3-dioxolane isused to produce the dioxole. A multi-plate distillation column may beused to separate the cis and trans isomers. Preferably, the cis isomeras well as 2,2-bis(perhaloalkyl)-4,4,5, 5-tetrachloro-1,3-dioxolane and-4-fluoro-4,5,5-trichloro-1,3-dioxolane are recycled to the fluorinationstep.

The dioxole in turn may be used to prepare homopolymers and copolymerswhich possess advantageous properties such as chemical inertness tohydrogen fluoride, optical clarity and film-forming ability.

For example, the dioxoles may be copolymerized under standardpolymerization conditions with tetrafluoroethylene to form crystallinecopolymers suitable for use as a dielectric in electronic equipment.Preferably, in these applications the dioxole is employed in an amountof about 12 mole % or less.

Polymers having more than about 12% dioxole are more generallyamorphous, and are soluble in various organic liquids, e.g.,1,1,2-trichloro-1,2,2-trifluoroethane. These polymers are useful in theproduction of chemically inert, stain and weather resistant coatings andfinishes.

Further, the dioxoles may be reacted with vinylidene fluoride ortetrafluoroethylene to produce plastic and/or elastomeric terpolymersuseful in the production of corrosion-resistant seals, gaskets orlinings.

Finally, the dioxoles may be homopolymerized to produce amorphous resinssuitable for use as transparent glazing materials and sight glasses inapparatuses employed in handling chemically corrosive materials.

In particular, the amorphous polymers are useful in the production ofoptical fiber cladding materials, e.g., in accordance with U.S. Pat.Nos. 4,530,569 and 4,754,009.

Various fluoropolymers have been proposed from time to time for thispurpose, mainly because of their good performance under a variety oftemperature and atmospheric conditions and resistance to many chemicals.A good polymeric cladding material for optical fibers should becompletely amorphous because crystallites present in polymers wouldcause light scattering. Further, it should have a high glass transitiontemperature, Tg, especially if intended for use at high temperaturesbecause above its Tg, it would lose some of its desirable physicalproperties; and, in particular, it would be unable to maintain goodbonding to the fiber core. A desirable Tg would be above 85° C.,preferably above 120° C.

As the amount of dioxole in the copolymer increases, the Tg alsoincreases, although not necessarily in a linear fraction.

A homopolymer of dioxole appears to be amorphous and has a high Tg.However, dioxole is a much more expensive monomer thantetrafluoroethylene so that use of dioxole homopolymers, rather than ofdioxole/tetrafluoroethylene copolymers, is economically much lessattractive. Furthermore, the copolymers are easier to fabricate. Thedipolymers have low refractive indices, which is a particularlydesirable feature for optical fiber cladding. Furthermore, films ofthese copolymers are clear and transparent, compared with hazy ortranslucent films of crystalline polymers. For this reason, theamorphous copolymers of the present invention are suitable for suchapplications as, for example, windows for chemical reactors, especiallyfor processes using or manufacturing hydrogen fluoride.

Amorphous terpolymers can be made by copolymerizing certainethylenically unsaturated monomers withperfluoro-2,2-dimethyl-1,3-dioxole and tetrafluoroethylene. Theseinclude selected olefins, vinyl compounds, and perfluoromonomers.Typical olefins are, for example, ethylene, propylene, 1-butene,isobutylene, trifluoropropene, and trifluoroethylene. Vinyl monomers canbe, for example, vinyl fluoride, vinylidene fluoride, andchlorotrifluoroethylene. Perfluoromonomers may be of different chemicaltypes, for example, perfluoropropene, perfluoro(1,3-dioxole),perfluoro(alkyl vinyl ethers), methyl3-[1-[difluoro(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy]-2,2,3,3-tetrafluoropropanoate ##STR6## and2-[1-[difluoro[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluorooethoxy]-1,1,2,2-tetrafluoroethanesulfonyl fluoride ##STR7##

The proportion of dioxole in the amorphous terpolymers of this inventionshould preferably be at least 12 mole percent of the tetrafluoroethylenecontent, while the mole percent content of the third monomer should bethe smallest of all three monomers. Outside these limits, either anamorphous terpolymer may not be obtained; or, if made, its maximumtensile modulus and strength may not be realized.

Copolymerization is carried out in the presence of a free radicalgenerator, preferably at a slightly elevated temperature, for example,55°-65° C. Well-agitated pressure equipment should be used.

In addition to tetrafluoroethylene, amorphous copolymers may befabricated from the dioxole and chlorotrifluoroethylene; vinylidenefluoride; hexafluoropropylene; trifluoroethylene; perfluoro(alkyl vinylethers) of the formula CF₂ ═CFOR_(F), where R_(F) is a normalperfluoroalkyl radical having 1-3 carbon atoms; fluorovinyl ethers ofthe formula CF₂ ═CFOQZ, where Q is a perfluorinated alkylene radicalcontaining 0-5 ether oxygen atoms, wherein the sum of the C and O atomsin Q is 2 to 10, and Z is a group selected from the class consisting of--CN, --COF, and --OCH₃, where R is a C_(L-C4) alkyl; vinyl fluoride;and (perfluoroalkyl)ethylene, R_(f) CH═CH₂, where R_(f) is a C_(L-C8)normal perfluoroalkyl radical.

The maximum preferred mole percentage of the comonomer in the copolymersare as follows:

for tetrafluoroethylene, 35;

for chlorotrifluoroethylene, 30

for vinylidene fluoride, 20;

for hexafluoropropylene, 5;

for trifluoroethylene, 30;

for CF₂ ═CFOR_(F), 30;

for CF₂ ═CFOQZ, 20;

for vinyl fluoride, 25; and

for R_(f) CH═CH₂, 10.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following preferred specific embodiments are,therefore, to be construed as merely illustrative and not limitative ofthe remainder of the disclosure in any way whatsoever.

In the preceding text and the following examples, all temperatures areset forth uncorrected in degrees Celsius and all parts and percentagesare by weight, unless otherwise indicated. Amounts of compounds listedin the Tables are given in area %. C.T. represents contact time.

In the following examples, the numbers identifying the compounds in thetables are as follows:

D456 - 2,2-Bis(trifluoromethyl)-1,3-dioxolane

D436 - 2,2-Bis(trifluoromethyl)-4,5-dichloro-1,3-dioxolane

D436a - 2,2-Bis(trifluoromethyl)-4,4-dichloro-1,3-dioxolane

D426 - 2,2-Bis(trifluoromethyl)-4,4,5-trichloro-1,3-dioxolane

D416 - 2,2-Bis(trifluoromethyl)-4,4,5, 5-tetrachloro-1,3-dioxolane

D417 - 2,2-Bis(trifluoromethyl)-4-fluoro-4,5, 5-trichloro-1,3-dioxolane

D418a - 2,2-Bis(trifluoromethyl)-4,4-difluoro-5,5-dichloro-1,3-dioxolane

D418 - 2,2-Bis(trifluoromethyl)-4,5-dichloro-4,5-dichloro-1,3-dioxolane

D419 - 2,2-Bis(trifluoromethyl)-4,4,5-trifluoro-5-chloro-1,3-dioxolane.

E X A M P L E S General Procedure for Chlorination

The reactor (0.5 inch ID Inconel nickel alloy pipe) was charged with thedesignated amount of catalyst, sealed and placed into a sand bath. Thebath was heated to 400° C., at which time nitrogen gas at a flow rate of50 ml/minute was passed through the reactor to remove all traces ofwater. Chlorine gas at a flow rate of 25.7 cc/min was passed through thereactor and the temperature adjusted to the desired value. The flow ofnitrogen gas was turned off and the flow of D456 started. The flow ofchlorine and D456 were adjusted to give the desired molar ratio.

The reactor effluent was scrubbed with aqueous potassium hydroxide toremove Cl₂, HCl and HF and sampled on line by a HP 5890 gaschromatograph using a 5 foot Krytox perfluorinated polyether column.Conditions were 70° C. for 3 minutes followed by temperature programmingto 180° C. at a rate of 6° C./minute. Helium flow was 35 cc/minute.

General Procedure for Fluorination

The reactor (0.5 inch ID Inconel nickel alloy pipe) was charged with thedesignated amount of catalyst, sealed and placed into a sand bath. Thebath was heated to 400° C., at which time nitrogen gas at a flow rate of50 ml/minute was passed through the reactor to remove all traces ofwater. The temperature was lowered to 200° C., and HF and nitrogen gas(1:4 molar ratio) was passed through the reactor, and the nitrogen flowwas decreased with time until neat HF was being passed through thereactor. At this point, the temperature is raised to 350° C. andmaintained there for 15 to 30 minutes. The temperature is then decreasedto the desired temperature, and the D416 flow is started. The flow of HFand D416 were adjusted to give the desired molar ratio.

The reactor effluent was scrubbed with aqueous potassium hydroxide toremove Cl₂, HCl and HF and sampled on line by a HP 5890 gaschromatograph using a 5 foot Krytox perfluorinated polyether column.Conditions were 70° C. for 3 minutes followed by temperature programmingto 180° C. at a rate of 6° C./minute. Helium flow was 35 cc/minute.

Examples 1-16

    ______________________________________                                        Chlorination of 2,2-Bis(trifluoromethyl)-1,3-Dioxolane (D456)                 CuCl.sub.2 /C 19.7 grams (30 cc)                                              Exp  Temp     Cl.sub.2 /D456                                                                         C.T.  D436 D426  D416 Unk                              ______________________________________                                         1   225      6/1      30    14   40    43   3                                 2   235      6/1      30     5   29    62   3                                 3   245      6/1      30     3   21    74   2                                 4   255      6/1      30     1    9    88   2                                 5   265      6/1      30     0    5    93   2                                 6   195      6/1      60    43   33    16   8                                 7   205      6/1      60    25   44    24   5                                 8   215      6/1      60    10   44    42   4                                 9   225      6/1      60     5   34    57   3                                10   235      6/1      60     1   18    80   1                                11   245      6/1      60     0    7    90   3                                12   255      6/1      60     0    2    95   3                                13   265      6/1      60     0    0    97   3                                14   275      6/1      60     0    0    96   4                                15   285      6/1      60     0    0    95   5                                16   285      4/1      60     0    1    95   4                                ______________________________________                                    

The conversion of D456 to products was 100%, as shown in the Table.

EXAMPLES 17-23

    ______________________________________                                        Chlorination of 2,2-Bis(trifluoromethyl)-1,3-Dioxolane (D456)                 CuCl.sub.2 /C 19.7 grams (30 cc)                                              Exp  Temp     Cl.sub.2 /D456                                                                         C.T.  D426 D416  D417 Unk                              ______________________________________                                        17   265      6/1      60    1    97    0    2                                18   265      6/1      60    1    97    0    1                                19   265      6/1      60    1    97    0    3                                20   265      5/1      75    1    97    1    0                                21   265      4/1      75    3    95    0    2                                22   265      5/1      60    2    95    0    3                                23   275      5/1      60    0    97    0    2                                ______________________________________                                    

The conversion of D456 to products was 100%, as shown in the Table.

EXAMPLES 24-28

    ______________________________________                                        Chlorination of 2,2-Bis(trifluoromethyl)-1,3-Dioxolane (D456)                 LaCl.sub.3 /C 4.25 grams (5 cc)                                                            Cl.sub.2 /                                                       Exp  Temp    D456   C.T. D456 D436 D426 D416 D417 Unk                         ______________________________________                                        24   200     6/1    10   3    74   12   10   0    1                           25   225     6/1    10   4    64   11   18   0    3                           26   250     6/1    10   1    43    9   43   1    2                           27   275     6/1    10   0    22    6   67   1    4                           28   300     6/1    10   0     9    3   72   3    13                          ______________________________________                                    

EXAMPLES 29-32

    ______________________________________                                        Chlorination of 2,2 Bis(trifluoromethyl)-1,3-Dioxolane (D456)                 SnCl.sub.2 /C 4.0 grams (5 cc)                                                             Cl.sub.2 /                                                       Exp  Temp    D456   C.T. D436 D426 D416 D427 D417 Unk                         ______________________________________                                        29   225     6/1    10   36   37   23   1    0    2                           30   250     6/1    10   13   29   53   1    1    3                           31   275     6/1    10    2    8   74   1    2    8                           32   275     5/1    10    2    9   70   0    2    12                          ______________________________________                                    

The conversion of D456 to products was 100%, as shown in the Table.

EXAMPLES 33-37

    __________________________________________________________________________    Chlorination of 2,2-Bis(trifluoromethyl)-1,3-Dioxolane (D456)                 FeCl.sub.3 /C 3.4 grams (5 cc)                                                Exp                                                                              Temp Cl.sub.2 /D456                                                                     C.T.                                                                             D456                                                                              D436                                                                             D426                                                                             D416                                                                              D427                                                                             D417                                                                             Unk                                       __________________________________________________________________________    33 200  6/1  10 11  36 2  8   4  0  39                                        34 150  6/1  10 36  51 1  0   3  0   9                                        35 200  6/1   1 67  21 1  1   2  1   7                                        36 250  6/1   1 37  25 1  6   3  0  28                                        37 250  4/1   1 42  19 1  5   2  0  31                                        __________________________________________________________________________

EXAMPLES 38-41

    ______________________________________                                        Chlorination of 2,2-Bis(trifluoromethyl)-1,3-Dioxolane (D456)                 ZnCl.sub.2 /C 3.8 grams (5 cc)                                                             Cl.sub.2 /                                                       Exp  Temp    D456   C.T. D456 D436 D426 D416 D417 Unk                         ______________________________________                                        38   200     6/1    10   27   62    5    4   0    2                           39   225     6/1    10   15   70   10    4   0    1                           40   250     6/1    10    7   66   15   11   0    1                           41   275     6/1    10    1   28   13   50   2    6                           ______________________________________                                    

EXAMPLES 42-51

    __________________________________________________________________________    Fluorination of                                                               2,2-Bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-Dioxolane                    Cr.sub.2 O.sub.3 28.9 g (30 cc) -12 + 20 mesh                                 Exp                                                                              Temp                                                                              HF/D416/HCl                                                                           C.T.                                                                             D419                                                                             tD418                                                                             cD418                                                                             D418a                                                                             D417                                                                             D416                                                                             Unk                                    __________________________________________________________________________    42 175 2/1/0   60  2 74  18  0   4  0  1                                      43 200 2/1/0   60 37 10   3  36  10 1  0                                      44 165 2/1/0   60 19 37   9  13  20 1  1                                      45 175 2/1/0   60 15 62  16  2   5  0  0                                      46 175 3/1/0   45  3 77  19  0   0  0  1                                      47 175 3/1/4   45 13 66  18  1   2  0  0                                      48 175 4/1/4   40  4 75  20  0   2  0  0                                      49 175 5/1/4   35  3 75  20  0   1  0  1                                      50 175 5/1/4   40  3 75  20  0   1  0  1                                      51 175 5/1/4   40  4 74  20  0   1  0  1                                      __________________________________________________________________________     t = trans                                                                     c = cis                                                                  

EXAMPLES 52-54

    ______________________________________                                        Fluorination of 2,2-Bis-trifluoromethyl)-4,4,5,5-                             tetrachloro-1,3-Dioxalane                                                     CoCl.sub.2 /C 12.3 g (30 cc)                                                               HF/                                                              Exp  Temp    D416      C.T.  tD418 cD418 D417 Unk                             ______________________________________                                        52   200     10/1/0    30    44    35    8    7                               53   200      5/1/0    60    39    33    16   6                               54   165     10/1/0    30    47    37    8    3                               ______________________________________                                    

EXAMPLES 55-59

    ______________________________________                                        Fluorination of 2,2-Bis(trifluoromethyl)-4,4,5,5-                             tetrachloro-1,3-Dioxolane                                                     Cr.sub.2 O.sub.3 14.4 g (15 cc) -12 + 20 mesh                                              HF/                                                              Exp  Temp    D416   C.T.  D419 tD418 cD418 D417 Unk                           ______________________________________                                        55   200     3/1/0   30   1    72    22    0    5                             56   200     3/1/0   30   0    71    26    0    3                             57   210     3/1/0   30   1    73    24    0    2                             58   220     3/1/0   30   1    72    24    0    3                             59   230     3/1/0   30   l    73    23    1    2                             ______________________________________                                    

COMPARATIVE EXAMPLES 60-68

    ______________________________________                                        Fluorination of                                                               2,2-Bis(trifluoromethyl)-4,4,5,5,-tetrachloro-1,3-Dioxolane                   LaCl.sub.3 /C 4.25 g (5 cc)                                                                HF/                                                              Exp  Temp    D416    C.T. tD418 cD418 D417 D416 Unk                           ______________________________________                                        60   225     2/1/0   10    2     4    85   3    6                             61   250     2/1/0   10   14    13    67   0    5                             62   275     2/1/0   10   26    27     0   0    4                             63   300     2/1/0   10   34    33    26   0    7                             64   300     2/1/0   20   43    35    11   0    10                            65   300     2/1/0   20   44    36     9   0    11                            66   250     2/1/0   40   41    38    14   0    7                             67   250     2/1/0   40   38    35    20   0    7                             68   300     2/1/0   40   46    31     4   0    11                            ______________________________________                                    

EXAMPLES 69-72

    ______________________________________                                        Fluorination of                                                               2,2 Bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-Dioxolane                    FeCl.sub.3 /C 3.4 g (5 cc)                                                                 HF/                                                              Exp  Temp    D416    C.T. tD418 cD418 D417 D416 Unk                           ______________________________________                                        69   200     2/1/0    5   0     0     24   71   5                             70   225     2/1/0    5   0     0     42   54   8                             71   275     2/1/0   10   7     8     76    1   8                             72   275     3/1/0   10   9     10    70    0   11                            ______________________________________                                    

EXAMPLES 73-79

    ______________________________________                                        Fluorination of                                                               2,2-Bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-Dioxolane                    NiCl.sub.2 /C 1.66 g (3 cc)                                                   1/8-inch Pellets                                                                           HF/                                                              Exp  Temp    D416    C.T. tD418 cD418 D417 D416 Unk                           ______________________________________                                        73   200     2/1/0   5    0     0      5   91    4                            74   220     2/1/0   5    0     0      7   88    5                            75   240     2/1/0   5    0     0     13   80    7                            76   260     2/1/0   5    0     0     31   61    6                            77   280     2/1/0   5    1     2     45   39   10                            78   280     4/1/0   5    5     4     66   10   13                            79   325     4/1/0   5    8     7     34    2   48                            ______________________________________                                    

EXAMPLES 80-83

    ______________________________________                                        Fluorination of                                                               2,2-Bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-Dioxolane                    CuCl.sub.2 /C 19.7 g (30 cc)                                                               HF/                                                              Exp  Temp    D416    C.T. tD418 cD418 D417 D416 Unk                           ______________________________________                                        80   200     3/1/0   30   2     2     66   13   16                            81   200     3/1/0   30   6     5     73   3    13                            82   250     3/1/0   30   4     4     85   0     5                            83   250     3/1/0   30   4     4     85   0     6                            ______________________________________                                    

EXAMPLES 84-85

    ______________________________________                                        Fluorination of                                                               2,2 Bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-Dioxolane                    SnCl.sub.2 /C 4.0 g (5 cc)                                                                 HF/                                                              Exp  Temp    D416    C.T. tD418 cD418 D417 D416 Unk                           ______________________________________                                        84   275     2/1/0   10    9    10    74   2    5                             85   275     2/1/0   20   19    17    60   0    4                             ______________________________________                                    

EXAMPLES 86-87

    ______________________________________                                        Fluorination of                                                               2,2 Bis(trifluoromethyl)-4,4,5,5-tetrachloro-1,3-Dioxolane                    ZnCl.sub.2 /C 3.8 g (5 cc)                                                                 HF/                                                              Exp  Temp    D416    C.T. tD418 cD418 D417 D416 Unk                           ______________________________________                                        86   300     2/1/0   10   6     7     73   10   4                             87   250     2/1/0   10   1     2     53   44   1                             ______________________________________                                    

EXAMPLE 88 Examples Describing the Rearrangement of Cis-D418 toTrans-D418

A mixture of 150 g D-418 (65.5% trans isomer), 6.0 g antimonypentachloride, and 20 g anhydrous hydrogen fluoride was heated at 100°for one hour and 135° for five hours. The reaction mixture was added toice/ice water and the lower layer washed with 400 ml ice water to give139.3 g of product. Analysis showed this product to contain 1.3 g D-419and 138.0 g D-418 (79.8% trans isomer). Thus the amount of trans D-418rose from 98.3 g to 110.1 g, while the amount of cis isomer fell from51.7 to 27.9 g.

A mixture of 40.5 g D-418 (53.5% trans isomer), 4.0 g antimonypentachloride, and 20 g anhydrous hydrogen fluoride was heated at 100°for one hour and 135° for four hours. The reaction mixture was added toice/ice water and the lower layer separated to give 35.4 g of productcontaining 26.7 g trans D-418 and 8.5 g cis D-418 (78.4% trans isomer).Thus the amount of trans D-418 rose from 21.7 g to 26.7 g, while theamount of cis D-418 declined from 18.8 g to 8.5. g.

EXAMPLE 89 Variation in Yield ofPerfluoro-2,2-bistrifluoromethyl-1,3-dioxole (PDD) with cis/transbis-2,2-trifluoromethyl-4,5-dichloro-4,5-difluoro-1,3-dioxolane (D418)

A mixture of 24.9 g magnesium turnings and 395 ml tetrahydrofuran washeated 60°. After addition of 2.75 ml, 1,2-dibromoethane approximately4.5 g bis-2,2-trifluoromethyl-4,5-dichloro-4,5-difluoro-1,3-dioxolane(D418) was added. The reaction mixture was cooled to 35°-40° and a totalof 133 g cis/trans D418 added. After stirring for 15 minutes, themixture was distilled until the pot temperature reached 70°. Thedistillate boiling to 45° was washed with 100 ml of ice water. Gaschromatographic analysis of the lower layer showed it to be greater than99% PDD.

    ______________________________________                                        Percent Trans Isomer                                                                           Yield of PDD                                                 in Startinq D418 Percent                                                      ______________________________________                                        97.7             60 7                                                         83.6             51.7                                                         64.7             40.2                                                         ______________________________________                                    

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

What is claimed is:
 1. In a process for the preparation of a polymerformed from monomers which comprise 2,2-bis(perhaloalkyl)-1,3-dioxolesof the formula ##STR8## where each R_(f) independently is perhaloalkylin which the alpha carbon atom is substituted by at least one fluorineatom, the improvement comprising:separatingtrans-2,2-bis(perhaloalkyl)-4,5-difluoro-4,5-dichloro-1,3-dioxolanesfrom a mixture of cis and trans isomers, and preparing the dioxoles bydehalogenating said trans isomers.
 2. A process according to claim 1,wherein the polymer is produced by homopolymerization of the dioxole,copolymerization of the dioxole with tetrafluoroethylene orcopolymerization of the dioxole with vinylidene fluoride.
 3. In aprocess for the preparation of a polymer formed from monomers whichcomprise 2,2-bis(perhaloalkyl)-1,3-dioxoles of the formula ##STR9##wherein each R_(f) independently is perhaloalkyl in which the alphacarbon atom is substituted by at least one fluorine atom, theimprovement comprising preparing the dioxoles by dehalogenatingcorrespondingtrans-2,2-bis(perhaloalkyl)-4,5-difluoro-4,5-dichloro-1,3-dioxolanesproduced by enhancing the amount of trans-isomers in a mixture of cis-and trans-isomers by rearranging cis- to trans-isomers.